This invention is related generally to the field of cutting of graphics areas or the like from sheets for various purposes, and other narrow-path-processing with respect to graphics areas on sheets.
The technical field involving the cutting of graphic areas from sheets, or otherwise doing narrow-path-processing with respect to graphics images on sheets, includes, for example, the face-cutting of laminate sheets to form decals. More specifically, a graphics image area on the face layer of a laminate needs to be cut away from the remainder of the face layer so that the graphics area (decal) can subsequently be pulled away from the backing layer of the laminate and be applied elsewhere as intended. Highly accurate face-layer cutting about the graphics is obviously highly desirable.
This is but one example in which highly accurate sheet cutting (or other processing) is desirable. In many other situations, highly accurate sheet cutting which is desired may not involve face-cutting, but through-cutting, in which the full thickness of the sheet is cut about a graphics area on the sheet. And in many situations, rather than highly accurate cutting, highly accurate scoring, creasing, line embossing or the like, in each case, of course, along a line the varying direction of which is determined by the shape of the graphics area. Together these types of operations on sheets with respect to graphics areas thereon are referred to herein for convenience as xe2x80x9cnarrow-path-processing.xe2x80x9d For convenience, the prior art problems and the invention herein which solves such problems will be discussed primarily with reference to sheet-cutting apparatus.
A method and associated apparatus which addresses many of the problems encountered in such processing of sheet material is the i-cut(trademark) vision cutting system from Mikkelsen Graphic Engineering of Lake Geneva, Wis., and is the subject of U.S. patent application Ser. No. 09/678,594, filed on Oct. 4, 2000, and U.S. patent application Ser. No. 09/827,000, filed on Apr. 5, 2001.
The invention described in the first document is a method and apparatus for achieving highly improved accuracy in cutting around graphics areas in order to fully adjust for two-dimensional distortion in the sheets from which the graphics areas will be cut, including distortion of differing degrees in different directions on the sheet of material. The distortion may be from the printing process or from some other post-printing process such as material handling or during the cutting process itself. This invention also provides improved speed and accuracy in narrow-path-processing and greater efficiency of material usage.
The invention described in the second document is a method and apparatus for automatically and rapidly determining the position and orientation of a sheet of material on a work surface. When the placement of the sheet of material is not precisely controlled, the speed of the cutting or other narrow-path-processing system is often impaired because the system may require manual intervention to adjust the placement of the sheet of material so that the system can begin processing. Thus, the invention described in the second document provides further improved speed over the invention described in the first document.
In some cases, such as in the i-cut(trademark) system from Mikkelsen Graphic Engineering, a flatbed plotter is used. These are devices having a positionally-controlled cutting implement above a flat work surface on which the sheet to be cut rests. The cutting implements are controlled based on controller-supplied instructions based on the X-Y coordinates necessary to achieve cutting along the intended path, such as about the graphics area.
Achieving greater speed and overall efficiencies in cutting or other narrow-path-processing is a continuing challenge encountered in the field of graphics image processing. One source of inefficiency is the length of time required by the system to begin the cutting process after the sheet of material on which graphics areas have been previously printed are placed on the work surface of the cutting apparatus, either manually or by automatic sheet-feeding equipment. In either of these set-up situations, the cutting apparatus must determine the position and orientation of the sheet on the work surface in order to proceed accurately with the cutting process. If the operator or automatic sheet-feeder places the sheet of material on the work surface such that it is outside of the area or region of alignment on the work surface which the cutting system expects to find the sheet, manual intervention may be necessary to adjust the placement of the sheet to within the required initial region in order for the process to continue beyond this initial set-up step. A further source of inefficiency is the time-consuming step which may be required to allow the system to determine the initial position and orientation of the sheet on the work surface.
Despite the significant advances represented by the i-cut(trademark) system, further increases in efficiency (speed of operation) are highly desirable in automated cutting systems.
It is an object of this invention to provide an improved method and apparatus for precision cutting of graphics areas from sheets overcoming some of the problems and shortcomings of the prior art.
Another object of this invention is to provide an improved method and apparatus which increase the speed of cutting and other narrow-path-processing of sheet material.
Another object of this invention is to provide an improved method and apparatus which automate the cutting and other narrow-path-processing of sheet material as much as possible.
Another object of this invention is to provide a method and apparatus for reducing the time to determine sheet position and orientation in apparatus for precise cutting around graphics areas.
Still another object of this invention is to provide an improved method and apparatus for cutting and other narrow-path-processing with respect to graphics on sheet materials of various kinds.
These and other objects of the invention will be apparent from the following descriptions and from the drawings.
The instant invention overcomes the above-noted problems and shortcomings and satisfies the objects of the invention. The invention is an improved method and apparatus for cutting graphics areas from sheets, or other narrow-path-processing with respect to graphics images. Stated more broadly, the invention is an improved method and apparatus for narrow-path-processing with respect to graphics images on sheets, including by cutting, creasing, scoring or the like around such images. Of particular note is that the instant invention brings high speed and improved efficiency, including eliminating certain manual intervention, to the precision cutting of graphics images from sheets bearing such images, including in situations in which there has been distortion of various kinds in the sheets, including two-dimensional distortion.
The method of this invention is stated with respect to cutting graphics areas from a sheet of material bearing such graphics area and a plurality of registration marks in predetermined positions with respect to the graphics area. The plurality of marks includes a subset of the marks as initial-position/orientation-determining marks, printed on no more than one side of the graphics area.
The method is of the type which includes (a) placing the sheet on a sheet-receiving surface, (b) sensing the subset in the field of view of a main sensor to determine the position and orientation of the sheet and approximate positions of the plurality of marks, (c) sensing the precise positions of the marks, and (d) cutting the graphics area from the sheet in response to the precise positions of the marks with respect to the graphics area. The invention involves the addition of steps which enable the process to proceed when the subset is not in an expected location on the sheet-receiving surface. These steps include automatically determining the coordinate region of the subset on the sheet-receiving surface and, in response to such determining step, automatically repositioning the main sensor to the coordinate region such that the subset is within the field of view of the main sensor. This method allows the sensing of the registration marks to occur rapidly with a minimum of manual intervention and cutting (or other narrow-path-processing) to occur precisely, whether or not two-dimensional distortion of the sheet is present prior to cutting.
The coordinate region of the subset on the sheet-receiving surface is the area thereof which, when contained within the field of view of the main sensor, enables main-sensor sensing of the subset with precision sufficient to determine the position and orientation of the sheet of material on the sheet-receiving surface such that the various registration marks can be automatically found to enable subsequent precision sensing thereof.
In certain preferred embodiments of the invention, automatically determining the coordinate region of the subset includes moving the main sensor in a predetermined pattern surrounding the expected location of the subset and stopping the movement of the main sensor when the coordinate region of the subset is located within the field of view of the main sensor. In one such embodiment, movement of the main sensor is in the plane of the sheet-receiving surface. In another such embodiment, moving the main sensor includes rotating the main sensor such that the field of view changes.
In certain embodiments of the invention, the automatic determining step includes enlarging the field of view of the main sensor, thereby locating the coordinate region of the subset within an enlarged field of view. The main sensor is then repositioned, including shrinking the field of view of the main sensor, such that the subset is within the field of view of the main sensor. In one such embodiment, enlarging and shrinking the field of view of the main sensor is performed by zooming a lens of the main sensor. In another such embodiment, the enlarging and shrinking steps are performed by increasing and decreasing respectively the distance between the main sensor and the sheet-receiving surface.
In another embodiment of the invention, automatically determining the location of the coordinate region of the subset involves locating the coordinate region of the subset within the field of view of a secondary sensor.
In certain embodiments of the invention, automatic determination the coordinate region of the subset includes sensing directive indicia on the sheet of material which indicate the coordinate region of the subset, the directive indicia being outside the coordinate region of the subset. Directive indicia may be extra marks printed on the sheet of material, marks which are part of the final graphics product being processed, or edges and/or corners of the sheet of material itself, all of which can be used to indicate the location of the subset. In particular embodiments of the invention, the automatic determining step includes determining from the directive indicia the direction and distance from the expected location to the actual location and repositioning the main sensor by moving it in the determined direction for the determined distance.
The inventive apparatus is a device for cutting a graphics area from a sheet of material bearing such graphics area and a plurality of registration marks in predetermined positions with respect the graphics area. The plurality of registration marks includes a subset of the marks as initial-position/orientation-determining marks, printed on no more than one side of the graphics area. The device includes: a sheet-receiving surface; a main sensor for sensing the subset in the field of view of the main sensor to determine the position and orientation of the sheet and approximate positions of the plurality of marks and for sensing the precise positions of the marks; a cutter operatively connected to the sensor and movable about the sheet-receiving surface, the cutter cutting the graphics area from the sheet of material in response to the precise positions of the marks sensed by the main sensor; and a coordinate region locator which, if the subset is not in an expected location, automatically determines the coordinate region of the subset on the sheet-receiving surface and in response thereto automatically repositions the main sensor to the coordinate region such that the subset is within the field of view of the main sensor.
In highly preferred embodiments of the invention, the coordinate region locator includes a controller with a set of locating instructions for moving the main sensor in a predetermined pattern surrounding the expected location of the subset, and stopping the movement of the main sensor when the coordinate region of the subset is located within the field of view of the main sensor.
In certain preferred embodiments, the coordinate region locator includes a zoom lens on the main sensor and a controller with a set of locating instructions for (a) enlarging the field of view of the main sensor by zooming the lens, (b) locating the coordinate region of the subset within the enlarged field of view, (c) repositioning the main sensor in response to the locating step, and (d) shrinking the field of view of the main sensor by zooming the lens such that the subset is within the field of view of the main sensor.
Another embodiment of the coordinate region locator includes a main-sensor height adjustor and a controller with a set of locating instructions for (a) enlarging the field of view of the main sensor by increasing the distance of the main sensor from the sheet material, (b) locating the coordinate region of the subset within the enlarged field of view, (c) repositioning the main sensor in response to the locating step, and (d) shrinking the field of view of the main sensor by decreasing the distance of the main sensor from the sheet such that the subset is within the field of view of the main sensor.
In certain embodiments of the invention, the coordinate region locator includes a secondary sensor with a field of view larger than the field of view of the main sensor, and a controller with a set of locating instructions for (a) locating the coordinate region of the subset within the field of view of the secondary sensor, and (b) repositioning the main sensor in response to the locating step such that the subset is within the field of view of the main sensor.
In another embodiment of the invention, the coordinate region locator includes directive indicia printed on the sheet of material outside the coordinate region of the subset in predetermined positions and orientations with respect to the subset, and a controller with a set of locating instructions for determining the coordinate region of the subset by sensing the directive indicia, and repositioning the main sensor in response thereto, such that the subset is within the field of view of the main sensor.